The technique Gaudí used to design the church was to hang little bags of birdshot from strings. Gravity would pull these bags downwards, giving even weight distribution and stretching the strings to form a model structure, thus showing him the shapes and angles his pillars would need to be. By photographing the model, then inverting the photograph, Gaudí could then see the model as it should look. A replica of his model for the crypt is in the Museum under the Sagrada Família in Barcelona.

In 2000, local architects set about repairing the crypt. This took away aspects of the unfinished nature of the buildings. However it did present a more tourist-friendly structure, and now visitors can stand on the roof, what would have been the church floor.However it is used for worship